The operated a charter flight from London Gatwick. The crew had been called up from standby quite near to the departure. The aircraft was suffering from an issue with the Stick Shaker in which it would activate on the later stages of approach when the aircraft was above the stall speed. The crew had not been advised. After a normal flight to Kos the crew would contact ATC. They were advised it was still dark on the ground as the sunrise would be at 03:15. The early stages of the approach to Kos had been normal and the crew had not noticed any abnormalities. During the final stages the stick shaker would go off briefly 4 times. The crew realized the aircraft was a little high. During these final stages the flight engineer would notice the radio altitude dropping rapidly from 700ft to 300ft and then back up. During the last 400ft of approach the aircraft was 3 Degrees below the Glideslope. The crew would notice the aircraft losing altitude rapidly in the last few seconds before touchdown. The aircraft would land hard and the tail would impact the runway 310ft from the beginning. The aircraft suffered substantial damage to the structure near the rear bulkhead. The aircraft would taxi safely and nobody was injured. Probable Cause: The distraction of the flight engineer due to fluctuating altitude and fatigue lead to the lack of proper call outs to Alert the pilot flying of the current altitude.